Antimicrobial coatings are applied to substrates such as wound dressings, personal hygiene or sanitary products, clothing, packaging, furniture, construction materials, textiles and the like to make them sterile and prevent bacterial growth. Antimicrobial coatings find particular use in wound dressings as the exudate from the wound contained in an absorptive wound dressing typically encourages the growth of bacteria, resulting in infections that compromise wound healing.
Most antimicrobial coatings include antimicrobial agents that are not permanently bonded to the substrate and eventually leach from the coating or are released from it. Such coatings lose their efficacy over time and the microbes may develop resistance against the particular active agents. Antimicrobial wound dressings, for example, normally include low molar mass biocides or nanosilver that leach from the coating and affects bacterial growth in its immediate environment. Due to the mode of action and activity of biocides and nanosilver, antimicrobial efficacy is lost over time and cannot be regenerated. Moreover, the antimicrobial agents may in some instances have a toxic or harmful effect if concentrations are increased in an attempt to prolong efficacy.
There is thus a need for an antimicrobial coating that may be permanently bonded to a substrate and which has the required antimicrobial activity to protect the substrate and surrounding environment from microbial infection, whilst retaining its antimicrobial activity for extended periods of time.
The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge in the art as at the priority date of the application.